Solid Rocket Motor
Demonstration of Star Grain
The combustion area of a solid rocket motor with central, cylindrical port increases as the inner surface burns outwards. This increases the chamber pressure, maybe dramatically and to unwanted levels.
The burning area may be modified by giving the port some kind of folded shape. Depending on the exact shape of the grain, the area and chamber pressure can be kept more or less constant or it can follow a certain operational curve.
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| Fig. 1: Technician at Aurora Project Group prepares an early solid rocket test motor with star shaped port. |
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| Fig. 2: The above test motor brought to a halt after a 1-sec burn. Red curve is start shape, yellow curve is predicted shape. |
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| Fig. 3: Animation showing progression of burn. |